An air handling system for a heating, ventilation, and air conditioning (HVAC) system generally includes an air filter(s) for removing particulates from the airflow prior to the airflow being provided to an interior space of a building. In some air handling systems, the air filter(s) may be high-efficiency particulate air (HEPA) filters. The air filter(s) are inserted into a cabinet which essentially functions as a duct for the airflow. To ensure the air filter(s) are appropriately filtering air, it is generally necessary to seal any gaps between a filter mounting rack which holds the air filter(s) in place and the cabinet in which the air filter(s) are placed. It may be difficult to properly seal the gaps to prevent airflow from bypassing the air filter(s) due to, for example, manufacturing tolerances, or the like.